Coronary artery thrombosis and thrombolysis in baboons: the effect of atenolol treatment on myocardial infarct size

The effect of the beta-blocker atenolol on experimental infarctsize was studied in a non-human primate model. In 12 baboonsthrombosis of the left anterior descending coronary artery (LAD)was induced and atenolol (0·1 to 0·2 mg . kg^–1intravenously, sufficient to lower the heart rate by 20%) wasadministered 10 mm after the onset of ischaemia in six animals,whereas the others received placebo. Thrombolysis was induced60 mm after the onset of ischaemia by intravenous injectionof rt PA (12 µg. kg^–1. min^–1) in all animals. Heart rate dropped signficantly after atenolol injection (128±9beats . min^–1 versus 163±15 beats . min^–1,P<0001) and was also lower than in the control group (128±9beats. min^–1 versus 158±22 beats.min^–1, p<0·05).Blood pressure remained unchanged after atenolol treatment.As compared to the control group, atenolol limited infarct size,expressed as a percentage of left ventricular mass (4·6±1·9%versus 7·9±1·3%, P<0·05 or asa percentage of the perfusion area (26±8% versus 43%8%,P<0·05).